Light emitting devices (LEDs) are anticipated to be used in future high-efficiency lighting applications, such as displays and lights. Recently, micro LEDs have been developed for future high-efficiency lighting applications. One challenge associated with such devices is that the assembly of micro-scale components can be costly and complicated, making it difficult to achieve high assembly accuracy at a reasonable manufacturing cost.
Methods for the distribution or alignment of small devices onto a transparent substrate, such as glass or a polymer, to create light emitting devices are well known in the art. One cost-effective method is fluidic self-assembly, in which a liquid carrier medium of an ink or slurry is filled with small lighting devices, and allowed to flow over the substrate. The small lighting devices are carried across the substrate by fluid transport, and gravity is used to mechanically trap the small lighting devices in mechanical trapping sites on the substrate in the manufacturing process. However, in conventional fluidic self-assembly methods, when small devices with different sizes are trapped in trapping sites, the devices are often misaligned or disposed in the incorrect sites. Moreover, even when the devices are correctly aligned and disposed in the correct sites, the resulting surface of the light emitting device may not be planar, requiring a polishing step after assembly, which compromises the cost-effectiveness of the manufacturing process, and in some cases can undesirably alter the precise positioning of the small lighting devices.